Mechanical-thermal structure suitable for a space environment

Abstract

A monolithic mechanical-thermal structure which is suitable for a space environment is provided, in which the structure contains at least one hole. The walls of the hole are lined with filaments. The monolithic mechanical-thermal structure may be made of metal. And a process for manufacturing the structure is also provided.

Claims

1. A system to transfer heat suitable for a space environment, the system comprising: a monolithic metal mechanical-thermal structure, comprising: at least one hole, said hole comprising walls lined with filaments, the structure and the filaments constituting a single part made of the same material, a filament of the filaments having a first end fixed to the wall and a second end left free, a length of the filament being between 0.2 and 5 mm and a diameter of the filament being between 0.3 and 0.8 mm; and a pipe inserted in the hole, the filaments being greater in length than a distance separating an outside of the pipe from an inside of the hole, the filaments bending in response to the pipe being inserted into the hole and the filaments contacting the pipe, wherein heat is transmitted from the monolithic metal mechanical-thermal structure via the filaments to the pipe.

2. The system according to claim 1, in which the filaments are greater in length than a distance separating an outside of the pipe from an inside of the hole, such that the filaments bend when the pipe is introduced.

3. The system according to claim 2, in which the pipe is a liquid ammonia heat pipe.

4. The system according to claim 1, in which the pipe is a liquid ammonia heat pipe.

5. The system according to claim 1, in which the walls comprise between 30 and 100 filaments per square centimeter.

6. The system according to claim 1, in which a percentage of the wall surface covered with filaments is between 10 and 50%.

7. The system according to claim 1, in which the mechanical-thermal structure comprises aluminum.

8. The system according to claim 1, in which the walls are covered with grease, allowing better thermal conduction.

9. A process for producing the system according to claim 1, further comprising a first stage of manufacturing the mechanical-thermal structure by an additive manufacturing method, a second stage of manufacturing the pipe and a third stage of inserting a heat pipe inside the hole in the mechanical-thermal structure.

10. The process according to claim 9, in which the pipe is manufactured by an extrusion method.

11. The process according to claim 10, further comprising a stage of coating the walls of the hole in the mechanical-thermal structure with grease.

12. The process according to claim 9, further comprising a stage of coating the walls of the hole in the mechanical-thermal structure with grease.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be better understood by studying some embodiments described by way of example and in no way intended to be exhaustive which are illustrated in the attached drawings in which:

(2) FIG. 1 represents a mechanical-thermal structure according to one aspect of the invention and

(3) FIG. 2 represents an enlargement of the boxed area depicted in FIG. 1.

DETAILED DESCRIPTION

(4) FIG. 1 illustrates a mechanical-thermal structure 1 intended to be integrated in a radiator panel with integrated heat pipes, for example, for which heat pipes are necessary for thermal control.

(5) The mechanical-thermal structure 1 is made up of a unique material exhibiting a low coefficient of thermal elasticity, in which case the mechanical-thermal structure 1 comprises aluminum.

(6) The mechanical-thermal structure 1 exhibits a hole 2, the walls 1bis of the hole 2 being lined with filaments 3. In this case, all the walls 1bis of the hole 2 are lined with filaments 3. Alternatively, only certain walls are lined with filaments. The entire mechanical-thermal structure 1 is monolithic, in other words the structure 1 and the filaments 3 constitute a single part. A pipe 4 is inserted inside the hole 2 in the structure 1.

(7) In this case, the hole 2 exhibits a form as is represented in FIG. 1. Alternatively, the hole 2 exhibits a shape adapted to the pipe 4 which must be inserted therein. The hole 2 may naturally be open-ended or blind.

(8) The pipe 4 comprises aluminum, this material exhibiting a low expansion coefficient and good thermal conductivity. The profile of the pipe 4 may be circular or indented, so as to increase the exchange surface. The pipe 4 is produced by a standard method, extrusion for example.

(9) Advantageously, the mechanical-thermal structure 1 is associated with heat dissipating equipment 5.

(10) Hence, the thermal energy emitted by the dissipating equipment 5 is transferred to the associated mechanical-thermal structure 1. The heat transmitted to the mechanical-thermal structure 1 is transferred via filaments 3 to the heat pipe 4. In this case, the heat pipe 4 is a liquid ammonia heat pipe. The liquid ammonia contained in the heat pipe 4 is evaporated close to the dissipating equipment 5, the liquid ammonia condenses at a distance from the dissipating equipment 5 and transfers thermal energy to the mechanical-thermal structure 1, which dissipates the thermal energy into its environment, in this case, space.

(11) FIG. 2 represents an enlargement of the boxed area in FIG. 1. FIG. 2 illustrates a portion of the hole 2, the walls 1bis of the hole 2 being lined with filaments 3, allowing the transfer of thermal energy between the pipe 4 and the walls of the hole 2.

(12) Advantageously, the gap between the external dimensions of the pipe 4 and the internal dimensions of the walls 1bis of the hole 2 falls between 0.1 and 2.5 mm.

(13) Typically, the walls 1bis of the hole 2 comprise between 30 and 100 filaments per cm.sup.2.

(14) According to one embodiment of the invention, a filament 3 measuring 0.3 mm in diameter may be separated from another filament 3 by a gap of between 0.5 and 0.8 mm in both directions.

(15) Advantageously, the filament 3 is cylindrical in shape. Alternatively, the filament 3 is parallelepipedal in shape or cylindrical at its base and flattened in the zone of contact with the heat pipe.

(16) The filaments 3 exhibit a length of between 0.2 mm and 5 mm and a diameter of between 0.3 and 0.8 mm.

(17) Advantageously, the percentage of wall 1bis surface covered with filament is between 10 and 50%.

(18) When the pipe 4 is inserted inside the hole 2, the filaments 3 bend over half their length, which increases the thermal exchange surface between the pipe 4 and the structure 1 via the filaments 3. Advantageously, the walls 1bis of the hole 2 lined with filaments 3 are covered with thermal grease, further increasing the thermal exchange surface between the pipe 4 and the structure 1.

(19) According to another aspect of the invention, the mechanical-thermal structure 1 as described previously is produced from a process comprising a first stage of manufacturing the mechanical-thermal structure 1, a second stage of manufacturing the pipe 4 and a third stage of inserting the pipe 4 in the hole 2 in the mechanical-thermal structure. The method of manufacturing the mechanical-thermal structure 1 is additive manufacturing.

(20) This method is an additive manufacturing process involving the selective fusion of powder deposited layer by layer. After each layer is deposited, a laser beam selectively melts the powder, so as to construct the profile of the required part. The deposits thereby achieved are kept in an inert atmosphere, in order to avoid oxidation of the metal layers. This process, coupled with a model achieved by computer-aided design or CAD, makes it possible to implement the direct laser manufacturing process, which enables relatively complex functional parts to be produced. This production technique makes it possible to realize the structure 1 as described previously exhibiting a hole 2 and extremely fine, numerous filaments on the walls 1bis of the hole 2, allowing the transfer of thermal energy between the pipe 4 and the structure 1.